In signal transmission applications, the choice of coaxial cable for conducting the signal is usually determined by the distance between connection points, the signal frequency, the maximum bend radius required, and the connector space available in a particular transmitting and/or receiving device. The longer the cable and the higher the frequency used, the larger the outside diameter needs to be to prevent excessive signal loss. Traditional coaxial cable applications, such as cable TV, broadband data, and microwave signal transmission, employ coaxial cables with outer diameters of 0.25 to 1 inches for distance of 50 to 100 feet. In indoor equipment, the shorter distance requirements, typically 6-24 inches, the limitations of limited space and tighter bend radius requirements are overcome by using smaller coaxial cables with outer diameters of 0.1-0.14 inches. However, these small outer-diameter cables have to be used with a standard coaxial connector. FIG. 1 shows an existing technique for connecting mini-coaxial cables. The term “mini-coaxial cable” used throughout this document means a coaxial cable having a center conductor diameter larger than 0.1 mm and smaller than 0.8 mm, such as RG179 coaxial cable. As shown, a conventional mini-coaxial cable 10 includes an outer sheath 11, a braided sheath 12, an insulating spacer 13, and a center conductor 14; and a standard coaxial cable connector 15 includes an inner conducting body 16 and an insertion pin 17 for inserting into an axial guide way in the connector 15 to mechanically and electrically connect to the inner conducting body 16. The insertion pin 17 is provided in a rear end with a cylindrical recess 18. According to the prior art, the insertion pin 17 is first soldered to the center conductor 14 located at a stripped front end of the mini-coaxial cable 10. To solder the insertion pin 17 to the bare center conductor 14 requires electric power and clean and bright working environment. Once the mini-coaxial cable 10 with the insertion pin 17 soldered thereto has been assembled to the standard coaxial cable connector 15, the outer sheath 11 of the mini-coaxial cable 10 is clamped to the standard coaxial cable connector 15 using a known clamping tool.
The above-described manner of connecting the mini-coaxial cable to a standard coaxial cable connector is troublesome, and it is therefore desirable to develop a solder-free connecting structure for stably and firmly connecting the center conductor of a mini-coaxial cable to a standard coaxial cable connector.